There are many patent documents that teach processes for making alkali metal-containing compounds. Among these are Great Britain Patent Application No. 1,481,553, European Patent Application Nos. 168,111; 462,762; and 465,118; and U.S. Pat. Nos. 4,302,342 and 4,867,891. Although lithium is disclosed as a possible alkali metal in making many of these compounds, in most of these formulations potassium and especially sodium are taught as preferred metals. In none of these above patents are processes to make lithium-containing compounds specifically exemplified.
There are also patent documents that teach lithium containing compounds are useful in lubricating oil compositions. U.S. Pat. Nos. 3,351,552; 3,634,240; 3,990,979; and 4,012,330 are examples of patents that teach lithium succinates as corrosion inhibitors in lubricating oil compositions.
U.S. Pat. No. 3,990,979 teaches half lithium salts of aliphatic hydrocarbon substituted succinic anhydrides and acids, which are reacted with polyhydric alcohols to provide an effective rust and corrosion inhibiting additive. These half lithium salts can be solubilized with alkyl phenols as a solvent aid in a physical mixture to prevent gelling, possibly forming a lithium phenate complex.
U.S. Pat. No. 2,951,808 teaches thixotropic mono- and di-metal salts of salicylic acids as oxidation inhibitors in lubricating oil compositions, preferably in greases. While the salicylic acids can have C.sub.1 -C.sub.15 alkyl groups, all the examples teach salicylic acids that are free of alkyl groups. The metal salts can be lithium or sodium salts.
U.S. Pat. No. 4,176,075 teaches a grease formulation similar to U.S. Pat. No. 2,951,808, which also contain a dioxime compound. The metal salts can be lithium or sodium, and are thixotropic.
U.S. Pat. No. 3,711,407 teach suspensions of oil-insoluble lithium salts of salicylic acid prepared by saponifying an aliphatic alcohol ester of hydroxy benzoic acid and then removing water and alcohol formed in the reaction.
U.S. Pat. No. 4,497,931 teaches polymer compositions stabilized by the presence of soluble lithium ions. These compositions are formed from a molten mixture of polymer, antioxidant, and a lithium compound.
U.S. Pat. No. 3,492,229 teaches certain base fluids that are oxidatively stabilized by certain metal salts. The metal can be any alkali metal or bismuth or lanthanum. Specific lithium-ontaining compounds taught (Table I) are the phenoxy benzoate and phenyl azobenzoate.
There are many grease compositions that use lithium compounds, especially lithium salts of hydroxy fatty acids, as a thickener. For example, the above mentioned U.S. Pat. No. 2,951,808 teaches a mixed lithium/calcium soap of 12-hydroxy stearic acid.
U.S. Pat. No. 3,985,662 teaches grease compositions using a lithium methyl salicylate soap. Lithium methyl salicylate soaps are thixotropic solids.
There are a few patents that teach processes for making lithium-containing compounds used as lubricating oil detergents.
U.S. Pat. No. 4,797,217 teaches a process for making overbased lithium sulfonates from lithium hydroxide monohydrate (BN of at least 250). Control of water removal is described as being important to the process. It does not teach any specific formulations containing these compounds.
World Patent No. 92/18,587, in Example 9, teaches an overbased lithium carboxylate. It does not teach any specific formulations including this compound.
European Patent Application No. 731159 teaches overbased lithium sulfonates that have a BN of at least 240.
There are also many patent documents that teach formulations of alkali metal-containing compounds. Examples of these include U.S. Pat. Nos. 4,326,972; 4,952,328; 5,464,548; 5,486,300; and 5,490,945; and World Patent Nos. 87/01,722; 90/15,124; 92/18,588; 93/23,504; 93/23,505; and 95/34,619. Although lithium is disclosed as a possible alkali metal compound in the making of many of these formulations, potassium and especially sodium are taught as preferred metals.
U.S. Pat. No.4,129,508 teaches an additive mixture of at least one reaction product of a hydrocarbon-substituted succinic acid or anhydride with at least one polyalkylene glycol or monoether thereof, at least one organic basic metal salt, and at least one alkoxylated amine. The basic metal can be magnesium, calcium, barium, lithium, or sodium. Example 14 shows a lithium alkyl benzene sulfonate having an apparent BN of at least 200.
There are a few patents that teach mixtures of lithium containing compounds and Group II metal-containing compounds. For example, European Patent Application No. 731,159 teaches a mixture of an overbased lithium-containing sulfonate detergent and an overbased non-lithium containing detergent. Great Britain Patent Application No. 1,365,311, in Example One, teaches a lubricating oil composition that contains both a neutral lithium salt of a polyisobutenyl succinic anhydride and an overbased sulfurized calcium phenate.
U.S. Pat. No. 5,030,687 in Example One teaches an overbased phenate/salicylate detergent (BN of at least 242) that contains a mixture of calcium and alkali metals. The alkali metal can be lithium, sodium, or potassium.
None of the prior art teaches that low BN lithium salts of substituted hydrocarbaryls give excellent black sludge dispersancy and deposit control in lubricating oil compositions.
U.S. Pat. Nos. 2,951,808; 3,351,552; 3,492,229; 3,634,240; 3,711,407; 3,985,662; 3,990,979; 4,012,330; 4,129,508; 4,176,075; 4,302,342; 4,326,972; 4,497,931; 4,797,217; 4,867,891; 4,952,328; 5,030,687; 5,464,548; 5,486,300; and 5,490,945 are hereby incorporated by reference in their entirety for all purposes.